1. Field of the Invention
The present invention relates to a magnetic head supporting device for supporting a magnetic head for recording signals in and/or reproducing recorded signals from a magnetic recording medium having the shape of a disk.
2. Background Art
Magnetic disk driving apparatus for writing information in and/or reading recorded information from a magnetic recording medium having the shape of a disk, i.e., a magnetic disk, are used widely as external storage apparatus for information processing apparatus, such as personal computers and word processors. These magnetic disk driving apparatus are classified roughly into two types. Magnetic disk driving apparatus of the first type are used for driving flexible magnetic disks, i.e., so-called floppy disks, and those of the second type are used for driving rigid magnetic disks, i.e., so-called hard disks. Magnetic disk driving apparatus of the first type are used more widely, because flexible magnetic disks are easy to handle and are comparatively inexpensive.
The magnetic head of a conventional magnetic disk driving apparatus must be projected from the upper surface of a back plate by a large length to dispose the magnetic head with a very small clearance of several micrometers between the surface of the flexible magnetic disk and its extremity for high-density recording. Accordingly, a portion of the flexible magnetic disk corresponding to the magnetic head is deformed greatly to make the rotation of the flexible magnetic disk unstable, and such local deformation causes fatigue and permanent deformation in the flexible magnetic disk.
A magnetic disk driving apparatus disclosed in Japanese Patent No. 58-15870 has been invented to solve those problems in the conventional magnetic disk driving apparatus. This known magnetic disk driving apparatus comprises a slider disposed so that the surface of a rotating flexible magnetic disk extends close to its upper surface, and provided with a negative pressure creating surface having a rear end, with respect to the direction of movement of the flexible magnetic disk, communicating with the atmosphere, outer positive pressure creating surfaces formed respectively on the radially opposite sides of the negative pressure creating surface, and an inner positive pressure creating surface formed in the negative pressure creating surface and provided with an opening for receiving a magnetic head therein.
This slider is able to hold the magnetic head close to the flexible magnetic disk scarcely deforming the flexible magnetic disk. The negative pressure creating surface is sunk by a small depth relative to the outer positive pressure creating surfaces, the inner positive pressure creating surface is formed in the central portion of the negative pressure creating surface, and the magnetic head is embedded in the inner positive pressure creating surface.
When the slider is located in close proximity to the rotating flexible magnetic disk with minute gaps between the outer positive pressure creating surfaces and the flexible magnetic disk and between the inner positive pressure creating surface and the flexible magnetic disk, a positive pressure is created between the outer and inner positive pressure creating surfaces and the flexible magnetic disk and a negative pressure is created between the negative pressure creating surface and the flexible magnetic disk. Thus, radially alternate zones of positive pressure and negative pressure are formed between the slider and the flexible magnetic disk while the flexible magnetic disk is rotated. Accordingly, this magnetic head supporting device has the following advantages.
(1) The magnetic head need not be projected to penetrate a plane including the flexible magnetic disk.
(2) Since the size of the slider is very small as compared with the diameter of the flexible magnetic disk and intervals between the positive pressure creating surfaces and the negative pressure creating surface are very small, the deformation of a portion of the flexible magnetic disk corresponding to the slider is suppressed to a very small extent by the rigidity of the flexible magnetic disk.
(3) Since the flexible magnetic disk is held substantially in a plane during rotation, permanent deformation and fatigue of the flexible magnetic disk are prevented.
Recently, further increase in recording density has been desired. However, it is difficult to achieve a high recording density when the magnetic coupling of the flexible magnetic disk and the magnetic head is established with the least deformation of the flexible magnetic disk. The magnetic head supporting device disclosed in Japanese Patent Publication No. 58-15870 is unable to apply a sufficient loading pressure to the flexible magnetic disk for high-density recording because the slider forms radially alternate zones of positive pressure and negative pressure to suppress the deformation of the flexible magnetic disk, and establishes the magnetic coupling of the magnetic head and the flexible magnetic disk by utilizing the rigidity of the flexible magnetic disk.